Numerous compounds, including ethers, cyclic ethers, alcohols, including aliphatic, olefinic and acetylenic varieties, nitroalkanes, esters, and others have been employed in various combinations to stabilize the chlorinated hydrocarbons in the presence of various metals.
Sulfur-containing compounds have also been employed as stabilizers for methylchloroform, e.g. mercaptans and disulfides have been used as secondary inhibitors (U.S. Pat. No. 3,641,169) to prevent the reaction of acids with the epoxides employed as stabilizers. Such acids are frequently found in metal cleaning operations. Sulfoxides have also been taught as useful in combination with epoxides (U.S. Pat. No. 3,535,392) as stabilizers for methylchloroform. Dithianes and thioxanes are taught to stabilize methylchloroform against reaction with iron and aluminum (U.S. Pat. No. 3,384,673). Other sulfur compounds are disclosed as useful stabilizers in U.S. Pat. Nos. 3,439,051 (dithiin); 3,467,722 (trimethylene sulfide); and U.S. Pat. No. 3,763,048 (1,3-dithiolane, 1,3-oxathiolane).
It has now been discovered that an alkyl alkynyl sulfide, especially methyl 2-propynyl sulfide, is useful alone or in combination with other inhibitors for stabilizing methylchloroform.